[amandalmullins]

I am not sure when the first day of my period was, but it was somewhere between the 16th and the 21st of December. On January the 28 th I found out I was pregnant. I had sex with my husband the end of December and the first of January. I had sex with someone else on January the 9th. My husband and I never use any birth control. The other guy and I started to have sex for like 2 minutes and then he put a condom on. SO my question is who is likely to be the father?

[Credendovidis]

... who is likely to be the father?

From first day of period plus 11 to 21 days is the window during which one normally can fall pregnant.
16 + 11 to 21 = --> 27 dec to (37) 6 Jan
21 + 11 to 21 = --> (32) 1 Jan to (42) 11 Jan
So somewhere between 27 December and 11 January you fell pregnant.
And therefore it is not to be said who the father is. Both can be!
Your own husband is more likely to be the father, but also "the other guy" can be the father.
The fact that he put on a condom "after 2 minutes" may save you from a lot of problems, but in no way is any guarantee that he is not the father. Some men can release semen very early by small pre-ejaculation before normal full ejaculation.
To make fatherhood clear you need a DNA test , but that is normally only done after birth.
You did not supply racial information. It may be possible to see that immediately at birth, if "the other guy" is of a different race than both you and your husband. So you better prepare your husband in that case.
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Alas !
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As always : if you require more info, please let me know. If this solves your problem, please rate the answer provided! Feed back is always appreciated!
;)

[bkdaniels]

Typically, my guess would be your husbands. And although there is the possibility of becoming pregnant by either of the guys, pregancy is based more on sperm count.

As we learned in high school biology, when the male ejaculates (which is when semen leaves a male's penis), between 0.05 and 0.2 fluid ounces (1.5 to 6.0 milliliters) of semen is deposited into the vagina. Between 75 and 900 million sperm are in this small amount of semen, and they "swim" up from the vagina through the cervix and uterus to meet the egg in the fallopian tube.

The large majority of these sperm die. They die because of the unfriendly environment of the vagina, which is acidic, and because the mucus in the cervix above the vagina acts as a selective filter for the sperm. Only 1% of all the sperm released in an ejaculation successfully pass through the woman's vagina and cervix to reach the uterus (the womb). Even though, it takes only 1 sperm to fertilize the egg, the more sperm, the better your chance of becoming pregnant.

For example, when males suffer infertility, they are not able to conceive because not enough sperm is produced to successfully pass through the woman's vagina and cervix to reach the womb. Like wise, if a guy do not complete an entire ejaculation in you, chances are slim of sperm making it to the womb to be fertilized.

So, if the guy, other than your husband, did release semen it probably was not enough. In other words, which ever guy leaves the most semem, has the higher chance of being the father.

Hope this answers your question!